Cardiac arrest during cardiac catheterization is uncommon, and fatal arrest is rare. In the coronary artery surgery study (CASS), which includes 7553 patients, the mortality of coronary arteriography was 0.2%. In the past 11 years, we have studied at necropsy 12 patients with severe angina pectoris who died during or shortly after coronary angiography. Ten of the 12 patients were described elsewhere and in a recent 1-month period an additional 2 patients with unstable angina and fatal cardiac arrest during cardiac catheterization were studied at necropsy. Because the necropsy findings in patients with angina pectoris and fatal cardiac arrest in the peri-cardiac catheterization period are predictable, yet poorly recognized, a brief description of the latter 2 patients appeared justified. Clinical and necropsy findings in our 2 patients confirm previous morphologic observations in patients having fatal cardiac arrest during or shortly after cardiac catheterization for angina. Of our 10 patients previously examined at necropsy, 9 had narrowing of the LM greater than 75% in XSA (by atherosclerotic plaque in 7, and by thromboembolic material superimposed on plaque in 2). In addition, at least 3 of 4 major epicardial coronary arteries were narrowed 76-100% in XSA in all 10 patients. Severe narrowing of the LM coronary artery is often indicative of severe narrowing of the right, left anterior descending and left circumflex coronary arteries. Of 35 necropsy patients with fatal coronary heart disease and narrowing 76-100% in XSA of the LM coronary artery previously reported from our laboratory, 94% also had similar narrowing of the right, left anterior descending and left circumflex coronary arteries.